"Smash" had a great start on NBC in the 2012 mid-season, but then all but fell apart under the weight of an unfocused plot and a head-spinning population explosion in the cast. For many viewers, the extended Uma Thurman story arc was a final first-season straw.

It's rare for shows this broken to get fixed - even the first season of "Parks & Recreation" wasn't as screwed up as "Smash" became - but thanks to some tough decision-making and the arrival of a new executive producer, TV's backstage musical "Smash" is back and again ready to become the hit it deserves to be.

The second season kicks off with a terrific two-hour show Tuesday night that should be a textbook example to other show runners on how to bring the audience along as you make significant changes to a troubled show.

And in case we don't get that there's a new game afoot, co-star Katharine McPhee starts the show with a number from the in-development musical "Bombshell" called "Moving On."

That new game is overseen by Joshua Safran ("Gossip Girl"), the new executive producer, who is jettisoning several characters in the story about the creation of a Broadway musical about Marilyn Monroe.

The primary focus remains on the musical written by Julia and Tom Levitt (Christian Borle), and on whether Eileen can get it onto a Broadway stage with Karen Cartwright (McPhee) winning the lead role over archrival, and Broadway veteran, Ivy Lynn (Megan Hilty), who'd been sleeping with the brilliant but insensitive director Derek Wills (Jack Davenport).

In the first season, the Karen-Ivy rivalry should have worked as the central plot line, but over time, it became tiresome.

Meanwhile, Julia's extramarital affair, not to mention Karen's boyfriend cheating on her with Ivy, became little more than ugly distractions. Maybe we could believe Julia cheating on her husband once, but a second time? It just felt like a far too convenient plot mechanism with little grounding in Julia's character.

Some of the musical numbers still worked, but then there was that over-the-top Bollywood production number that was so giddily ridiculous, it almost felt like a classic jumping-the-shark moment. If it was, the shark was picking its teeth afterward.

The second-season premiere and subsequent episode re-chart the overall course for the show, giving us a somewhat more credible sense of how a Broadway show gets made and bringing the process into modern times with the introduction of two new characters.

Don't worry: The young songwriting team of Jimmy Collins (Jeremy Jordan, "Newsies" on Broadway) and Kyle Bishop (Andy Mientus, "Carrie," off-Broadway) are much more than just two other guys you have to keep track of.

While Tom, Julia and Derek work in Manhattan and Eileen does business at fancy lunches, Jimmy and Kyle support themselves as bartender and waiter while toiling away on their own rock musical in their cramped Brooklyn apartment.

Their world seems more than a couple of miles away from that of the "Bombshell" team, but the inevitable and believable intersection of "old" and "new" musical theater adds real life and renewed potential to "Smash."

There are other changes as well. Karen and Ivy aren't at each other's throats all the time but, instead, focused more on moving on, as the song says, one way or the other.

Karen, for one, is no longer the wide-eyed Midwesterner in the big city but instead is developing that all important thicker skin as a theater pro.

Also undergoing renovation, and none too soon, is Julia's wardrobe: At last, with Tom's urging, she'll ditch the scarves and stop resembling a mobile Bedouin tent whenever she enters a room.

The show also makes a much smarter use of music in the first two episodes than it had as its first season wore on. Instead of a heavy focus on production numbers from "Bombshell," there's more variety in the new songs, thanks largely to the young Brooklyn songwriters who craft tunes in a more contemporary Broadway style.

Her musical numbers, including a red-hot blues production number, as well as "I Got Love" and the original song, "I Can't Let Go" in the second episode, are not only terrific by themselves, they announce loud and clear that "Smash" is back on track. Let's hope it stays that way.